When a metal layer contacts with a lightly doped semiconductor material, a contact effect comparable to a PN-junction appears. It is called the Schottky contact. This effect is used to make Schottky diode. When forward biased, a Schottky diode is in an “on” state and current flows through the diode. When the diode is reversely biased, a Schottky diode is in an “off” state and ideally current will not flow. However, Schottky diodes are not ideal, and thus will experience a small amount of reverse leakage current. Reverse leakage is detrimental to the performance of a circuit and results in a loss of power in the circuit. The breakdown voltage of a Schottky diode is the maximum amount of voltage that may be applied to the diode before the diode begins to breakdown. Accordingly, a Schottky diode for high-voltage applications with low reverse leakage current and high forward current drivability is desired.
FIG. 1 shows a conventional Schottky diode 100. The electrical field between the Schottky contact 12 and the semiconductor material 11 needs to be minimized for reducing reverse current and achieving higher breakdown voltage. Accordingly, the conventional high voltage Schottky diode 100 adopts deep and lightly doped P-type ring 15 as a guard ring region to reduce the high electrical field near the Schottky contact 12.
FIG. 2 shows a layout diagram of the conventional Schottky diode 100 as shown in FIG. 1. Cathode contact region 14 is laid at the edge of the diode 100 and the guard ring region 15 is laid out at the periphery of the metal Schottky contact 12. For the conventional Schottky diode 100, deep guard ring region 15 is required to substantially reduce the electric field near the metal Schottky contact. However, deep guard ring region 15 consumes large area, and the integrating density is poor.
Accordingly, improved devices are desired to address the above deficiencies.